Method and apparatus for selected internet protocol traffic offload

ABSTRACT

A method and apparatus of offloading traffic in a wireless communication system is disclosed. The wireless communication system, for example, an evolved Node-B (eNB) comprises a transmitter, a receiver, and a processor. The transmitter is configured to transmit, to a wireless transmit/receive unit (WTRU), a broadcast system information (SI) message of a Long Term Evolution (LTE) system indicating that traffic off-load (TO) is supported. The transmitter is further configured to, after transmitting the broadcast SI message, transmit a non-access stratum (NAS) message to the WTRU, wherein the NAS message indicates that a TO service is available for the WTRU. The receiver is configured to receive, from the WTRU, a signaling for initiating TO service in response to at least the transmitted NAS message. The processor, operatively coupled to the transmitter and the receiver, is configured to communicate using the TO service while maintaining at least one bearer with the WTRU.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/987,644, filed on Jan. 10, 2011, which claims the benefit of U.S.Provisional Patent Application No. 61/293,423 filed on Jan. 8, 2010, andU.S. Provisional Patent Application No. 61/304,199 filed on Feb. 12,2010, the contents of which are hereby incorporated by reference herein.

BACKGROUND

Selected internet protocol (IP) traffic offload (SIPTO) is a method tooffload traffic from a wireless communication system operator's corenetwork to a defined IP network that is close to a point of attachmentto the access point of a wireless transmit receive unit (WTRU). Whenreference is made to a core network with respect to the data plane, thenodes under consideration include the serving gateway (SGW) and thepacket data network gateway (PDW) in, for example, a long term evolution(LTE) compliant system, or the serving general packet radio service(GPRS) support node (SGSN) and gateway GPRS support node (GGSN) in auniversal mobile telephone system (UMTS) terrestrial radio accessnetwork (UTRAN), although the disclosure herein is not limited to anyone network architecture or technology. The goal of SIPTO is to offloadsome of the IP traffic from traversing these nodes.

SIPTO may require that a WTRU may process both offloaded traffic andnon-offloaded, or non-SIPTO, traffic that goes through the operatorsnetwork. SIPTO may be used in, for example, a UTRAN, an evolved UTRAN(E-UTRAN) and a macro cell with a home eNodeB (HeNB), for example.

SUMMARY

A method and apparatus of performing selective internet protocol (IP)offload (SIPTO) or local IP access (LIPA) is disclosed. A wirelesstransmit receive unit (WTRU) receives a broadcast message from a Node-B.Then the WTRU receives a message from the Node-B that SIPTO service, orLIPA service is available for that WTRU. The WTRU then communicatesusing the SIPTO or LIPA service.

A method an apparatus for receiving a paging message for SIPTO or LIPAservices is also disclosed. The paging message includes an indicatorthat indicates that the message is for SIPTO or LIPA communications. Theindicator may be a temporary mobile subscriber identity (TMSI) assignedby the network specifically for SITPO or LIPA communications. Theindicator may also be a single bit designated to indicate that a pagingmessage is a for SIPTO or LIPA traffic.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is an example architecture of a wireless network configured toperform SIPTO;

FIG. 3 is an example flow diagram of procedure for indicating support ofSIPTO services;

FIG. 4 is an example flow diagram of a procedure for triggering deliveryof SIPTO service;

FIG. 5 is an example flow diagram of a procedure for stopping deliveryof SIPTO services; and

FIG. 6 is an example flow diagram of a paging procedure using SIPTO.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, a Home Node B, aHome, a site controller, an access point (AP), a wireless router, andthe like. While the base stations 114 a, 114 b are each depicted as asingle element, it will be appreciated that the base stations 114 a, 114b may include any number of interconnected base stations and/or networkelements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home , or access point, for example, and may utilize any suitable RATfor facilitating wireless connectivity in a localized area, such as aplace of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 106, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 106 and/or the removable memory 132.The non-removable memory 106 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 106.

The RAN 104 may include eNode-Bs 140 a, 140 b, 140 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 140 a, 140 b, 140c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 140 a, 140 b, 140 c may implement MIMO technology. Thus,the eNode-B 140 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 140 a, 140 b, 140 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1C, theeNode-Bs 140 a, 140 b, 140 c may communicate with one another over an X2interface.

The core network 106 shown in FIG. 1C may include a mobility managementgateway (MME) 142, a serving gateway 144, and a packet data network(PDN) gateway 146. While each of the foregoing elements are depicted aspart of the core network 106, it will be appreciated that any one ofthese elements may be owned and/or operated by an entity other than thecore network operator.

The MME 142 may be connected to each of the eNode-Bs 142 a, 142 b, 142 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 142 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the s 140 a, 140 b,140 c in the RAN 104 via the S1 interface. The serving gateway 144 maygenerally route and forward user data packets to/from the WTRUs 102 a,102 b, 102 c. The serving gateway 144 may also perform other functions,such as anchoring user planes during inter- handovers, triggering pagingwhen downlink data is available for the WTRUs 102 a, 102 b, 102 c,managing and storing contexts of the WTRUs 102 a, 102 b, 102 c, and thelike.

The serving gateway 144 may also be connected to the PDN gateway 146,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 108. In addition, the corenetwork 106 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 2 shows an example LTE system 200 configured to provide SIPTOservices. The system includes a WTRU 210 in communication with an eNB220 that is located in a radio access network (RAN) 225. The eNB 220 isalso in communication with S-GW 230, which is also in communication withL-PGW 235 and a core network (CN) 240. The CN 240 includes an MME 245and a P-GW 250.

The WTRU 210 communicates with the eNB 220 over a wireless air interface255. The eNB 220 also communicates with the S-GW 230 over an S1-Uinterface 260. The S-GW 230 communicates with the L-PGW 235 over an S5interface 265, and with the P-GW 250 over an S5 interface 270. The S-GW230 also communicates with the MME 245 over an S11 interface 275. Twotraffic streams are also shown, a SIPTO traffic stream 280 that isrouted through the S-GW 230 to the L-PGW 265, and a CN traffic stream285 that is routed through the S-GW 230 to the P-GW 250 in the CN 240.

The eNB 220 may also be a HeNB configured to perform SIPTO in a homenetwork of the user of the WTRU 210. In that case, traffic may beoffloaded locally to a user's home network. The home network may be anIP network that is connected to other devices such as a printer, atelevision, and a personal computer, for example. These nodes on thehome network may be using private addressing.

Also the system 200 may be configured to provide Local IP Access (LIPA).While many of the features disclosed herein are described with regard toSIPTO, they may also be applied to LIPA and SIPTO systems for HeNBs. Forexample, SIPTO or LIPA may include single or multiple packet datanetwork (PDN) connections, deployment behind network address translation(NAT), and the like.

Furthermore, for traffic going through the mobile operator's corenetwork, the S-GW 230 user plane functions may be located within the CN240. Also, mobility management signalling between a WTRU 210 and thenetwork may be handled in the CN 240. Session management signalling,such as bearer setup, for LIPA or SIPTO traffic, and traffic goingthrough the CN 240 may terminate in the CN 240. Also, reselection of aWTRU's offload point for SIPTO traffic that is geographically ortopologically close to the WTRU 210 may be possible during idle modemobility procedures.

The SIPTO system may include a local gateway that is close to a WTRU'spoint of attachment to the access network. The local gateway may performIP traffic offload based on some policy or configuration, for example,based on the IP address destination. IP traffic may go through the localgateway rather than through the operator's core network via, forexample, an S-GW and a P-GW or via an SGSN and a GGSN (not pictured).

Depending on the network technology, a local break point or localgateway may be in the HeNB subsystem or in a radio network controller(RNC). Also, the SGSN may be responsible for both control and user planein some networks, while the user and control planes are taken care of bya mobility management entity (MME) and an SGW in others.

A local gateway, such as the L-PGW 235, may have certain functionalitiesof a PDW/GGSN. For example, the local gateway may have the followingfunctionalities IP address allocation, direct tunneling with the RAN 225in connected mode, per WTRU policy based packet filtering, of ratepolicing/shaping. In order to perform SIPTO transfers to a network, suchas a local network or Intranet, for example, a proper PDN connection maybe required. A WTRU may set an access point name (APN) to a specificvalue when requesting a PDN connection or when requesting theestablishment of a packet data protocol (PDP) context.

FIG. 3 is a flow diagram showing an example trigger procedure 300 forthe WTRU to communicate using SIPTO or LIPA services. First, the eNode Bbroadcasts an indication of support of SIPTO or LIPA to indicate thatsuch a service is available in a network for some WTRUs, at 310. TheeNode B may then send a NAS message to a WTRU indicating that SIPTO orLIPA service is allowed for that WTRU, at 320. The WTRU may thencommunicate using the SIPTO or LIPA service, at 330.

It should be noted that the service indication of support for SIPTO orLIPA service may be broadcasted on a per cell basis, or for another areasuch as a routing area or tracking area. The indication may be broadcastin a system information message, for example. Further, the cell may be aCSG cell in the case of LIPA. The cell may also provide an indication ofthe availability of SIPTO or LIPA services in a NAS message such as anAttach Accept, TAU Accept, or RAU Accept for example.

The WTRU may also provide an indication of SIPTO or LIPA capability tothe network. This may be useful whether the WTRU supports SIPTO or LIPAfor macro cells, for HeNBs, or both. A WTRU and/or the network may alsoprovide an indication of support for SIPTO or LIPA in an LTE systemonly, UTRAN only, or both, or also any other combination of systemsincluding non-3GPP access.

The availability of SIPTO or LIPA service, the level of support, thetype of system, and the like may also be provided to the WTRU using anaccess network discovery and selection function (ANDSF). This may beprovided as a policy that helps the WTRU change or use certain accesstechnologies.

The indicators described herein may be used relative to a target systemor cell. For example, when the WTRU is performing inter-system change orpacket switched (PS) handover from one network to another, such as fromLTE to UTRAN, the indication of SIPTO or LIPA support in the targetsystem may be included in a mobility message such as theMobilityFromEUTRACommand. The indication may also be transmitted uponrelease of a radio resource control (RRC) connection with redirectioninformation. The WTRU may use the indication to trigger a PDP contextactivation to a certain GGSN or PDN connection to a specific PDW forinter-system change from UTRAN to E-UTRAN, for example. The WTRU mayalso be provided with a default access point name (APN) or it may derivethe APN based on its location. Alternatively, the APN may be leftundetermined or set to a random or unknown value. The network may choosethe appropriate gateway based on some policies. Indicators may also beused in an intra-system handover. The indications may be forwarded tothe upper layers, such as the NAS, in order to initiate any signalingthat is needed for SIPTO or LIPA services.

An indication about the support of SIPTO or LIPA for CSG cells may beused. The WTRU may maintain the indication for all or some of its CSGIDs in, for example, a white list, maintained by the access stratum, ora radio resource control (RRC) entity. Alternatively, the WTRU maymaintain the indication for all or some of its CSG IDs in the USIM, theallowed operator list maintained by the Non access stratum (NAS), or theoperator controlled list maintained by NAS.

The WTRU may be informed if the local gateway that serves the WTRU forSIPTO or LIPA is standalone or collocated with a CSG cell. The WTRU maydeactivate its PDN connection(s) either locally or by signaling thenetwork (MME 245 or SGSN) when the WTRU leaves its previous cell whereSIPTO or LIPA was provided. Moreover, the deactivation may avoid pagingthe WTRU for SIPTO or LIPA traffic when the WTRU is in idle mode.

FIG. 4 shows an example procedure 400 for triggering delivery of SIPTOservice. The procedure begins when the WTRU enters a specific area, suchas routing area (RA), tracking area (TA) or Local Area (LA) or camps ona CSG cell, at 410. Then the WTRU or network initiates the signaling forSIPTO, or the WTRU starts receiving SIPTO service, at 420.

The initiation of SIPTO or LIPA service occurs when the offload oftraffic occurs. The WTRU may be unaware of the offload process. SIPTO orLIPA initiation may also occur when the signaling that might be neededin order to offload selected traffic occurs, for example, when a new PDNconnection is needed.

The WTRU may trigger SIPTO or LIPA services when the WTRU enters aspecific tracking area identity (TAI) or routing area identity (RAI), ora specific service area. Alternatively, the WTRU may use an indicationit receives in a TAU Accept or a RAU Accept message in order to takespecific action, such as the establishment of a new PDN connection oractivation of a new PDP context, for example.

A trigger may occur when the WTRU camps on, or goes to, a CSG cell. TheWTRU may trigger a PDN connection even if it is unaware of whether SIPTOor LIPA is supported on a CSG cell. Otherwise, the WTRU may use theindications as set forth herein, for each CSG identity, to determinetriggering of any necessary signaling for SIPTO, such as establishmentof a new PDN connection or PDP context activation, for example.Alternatively, this may be done upon manual selection of CSG or macrocells.

A trigger may occur when a WTRU receives indications from the networkthat SIPTO or LIPA service is available using, for example, dedicatedsignaling such as an EPS mobility management (EMM) information messageor other NAS or radio resource control (RRC) messages.

If the establishment of a new PDN connection, activation of a new PDPcontext or modification of any bearer/context is required for SIPTO orLIPA, the network may also initiate the procedures. For example, a PDNconnection may be initiated by a WTRU. The network may initiate a PDNconnection towards the WTRU when the network decides to deliver SIPTO orLIPA services to the WTRU. This may be achieved using a sessionmanagement message. Alternatively, the network may directly send amessage, such as an Activate Default EPS Bearer Context to the WTRU. Asimilar message may be sent in a UTRAN for PDP context activation. Thenetwork may include the APN of the gateway that is performing trafficoffload for the WTRU. Moreover, the network may add an EPS sessionmanagement (ESM) cause to indicate that the connection is for SIPTO orLIPA service.

The WTRU may use any of the indicators disclosed herein to display tothe user of the WTRU any relevant information that is related to SIPTOor LIPA. The user may use the information for many purposes, such asstarting specific services, local file transfer, and the like.

The WTRU may provide preferences regarding traffic, such as preferencesas to which traffic should be offloaded. Other triggers may be relatedto quality of service (QoS). Any degradation in received QoS may triggerthe start of a SIPTO procedure so that traffic is diverted away from theCN.

At each connection establishment, the RAN may provide at least one IPaddress to the network nodes. The network nodes may then choose a localgateway for SIPTO or LIPA. However, at the point of connectionestablishment, the RAN may not know what data type, that is, SIPTO ornon-SIPTO, will be sent by the WTRU . Several gateways may be made readyas potential paths or routes for SIPTO or LIPA traffic. Alternatively, aHeNB gateway (GW) may receive at least the first user plane packetbefore it may suggest a routing path or a local gateway for SIPTO orLIPA. Alternatively, the choice of path or gateway may be made for eachbearer context or PDP context. An HeNB GW, or any other node that needsto take an action for SIPTO or LIPA service provision, such as the RAN,may decide whether packets should not go through the core network basedon mappings to certain bearer or contexts which are known to be SIPTO orLIPA affected. Specific bearers may be known to carry SIPTO or LIPAtraffic or non-SIPTO traffic.

The same triggers defined in relation to starting SIPTO or LIPA servicemay also be used to stop the delivery of SIPTO or LIPA services. Thenetwork may stop the offload of selected traffic, possibly without theWTRU being aware of the stopping of the service. The network may alsostop the exchange of signaling between the WTRU and the network, such asa request to disconnect from a PDN or to deactivate a PDP context. Thesignaling may be triggered by either the network or the WTRU. Inaddition, the WTRU and network may initiate an end to SITPO or LIPAservice delivery based on an expiration of a timer. For example, when nouser data is exchanged for a specific configurable or default time, thetimer may expire and SIPTO or LIPA service may be closed.

FIG. 5 shows an example procedure 500 for the WTRU to stop LIPA servicesif the WTRU's subscription on a CSG expires. The WTRU is connected to aCSG and communicates using LIPA services, at 510. The WTRU is handedover from a CSG from which LIPA service was provided, to a target cellon which LIPA service is not provided, at 520. Then, the WTRU maydeactivate any PDN connection locally without signaling to the MME, at530. Alternatively, the deactivated bearers may be signaled in othermessages, such as TAU or RAU requests and responses, for example.

The WTRU or a user of the WTRU may provide preferences about whattraffic should not be offloaded. Other triggers are possible and may berelated to QoS. For example, any degradation in received QoS may cause astop of SIPTO or LIPA and traffic may be diverted via the core network.

FIG. 6 shows an example procedure 600 for performing paging in a SIPTOenabled system. The procedure starts when the WTRU receives a pagingmessage including an indication that the paging message is for SIPTO anda CSG ID, at 610. Then the WTRU responds to the paging for SIPTO servicemessage, at 620. Then the network establishes resources for SITPObearers and the WTRU maintains non-SIPTO bearers, at 630.

The network may indicate to the WTRU that a paging message, sent via RRCsignaling, is due to SIPTO or LIPA traffic. A specific SIPTO or LIPAidentifier (ID) may be used for the page to differentiate the SIPTO orLIPA page from other pages. The ID may be similar to a temporary mobilesubscriber identity (TMSI) such as an S-TMSI or a P-TMSI, and may beassigned by the network when the SIPTO or LIPA service is initiated. Thenetwork may allocate this ID in a message, such as an NAS message. TheNAS message may be, for example, an Attach Accept, TAU Accept, RAUAccept, and the like. Additionally, a new core network domain identifierin the RRC paging message may be used to indicate that the paging is forSIPTO or LIPA. Also, a bit may be used to indicate that a paging messageis for SIPTO or LIPA traffic.

The WTRU may respond to the paging for SIPTO or LIPA by sending amessage, such as the NAS Service Request message, for example, oranother message for similar purposes. An establishment cause may be usedwhen a WTRU is requesting an RRC connection or NAS signaling connectionfor SIPTO or LIPA traffic.

If the WTRU requests an RRC connection, a NAS signaling connection, or amobile originating or terminating SIPTO or LIPA traffic and sends amessage, such as a Service Request message or other message with asimilar purpose, the radio and S1 bearers may not be established forenhanced packet service (EPS) bearer contexts that are used for trafficthat goes through the CN. In addition, the WTRU may not deactivate theEPS bearer contexts for which no radio or S1 bearers were established,and maintains the existing non-SIPTO bearers. The WTRU and the networkmay use other signaling, such as an RRC message(RRCConnectionReconfiguration) for example, to establish radio and S1bearers for CN traffic when it is available. The WTRU may also triggerestablishment of radio and S1 bearers by sending a message, such as anNAS or an RRC message.

In an embodiment, MME or SGSN functionality may be located in a localgateway. The local gateway may host a part of the total MMEresponsibilities that may be in the CN. Some of the local MME functionsmay include paging for SIPTO traffic and termination of a signalingpoint for SIPTO or LIPA and both mobility and session managementsignaling, for example. The local MME may communicate with the CN's MMEin order to update certain WTRU contexts in the network, such asestablishment of new bearers for SIPTO or LIPA traffic and disconnectingof PDN connections, for example.

The local gateway or any other local functionality, such as the trafficoffload point function, for example, may maintain some mobilitymanagement contexts for the WTRUs such as an S-TMSI, M-TMSI, or P-TMSIand an international mobile subscriber identity (IMSI), routing areaidentifier (RAI) and tracking area identifier (TAI), for example. Thelocal functionality may be useful where the local functionality maycontact the WTRU via paging to provide information to nodes such as theRNC or RRC, for example.

The WTRU may also deactivate idle mode signaling reduction (ISR) whenLIPA traffic on a home or enterprise network is started or when SIPTOtraffic on a home cell, enterprise CSG cells or macro cell is started.The deactivation may avoid the need to page the WTRU if the WTRUreselects between two systems and if the LIPA/SIPTO traffic cannot berouted to the target system.

In addition, the WTRU may initiate a tracking or routing area updateprocedure to inform the MME or SGSN, respectively, that the WTRU hasleft its previous cell where LIPA or SIPTO was activated. This mayrequire a new update type. The network and the WTRU may deactivate allrelated contexts and IP addresses. Alternatively, the network and theWTRU may maintain all related contexts and IP addresses. If the relatedcontexts and IP address are maintained, the WTRU may not be paged forLIPA/SIPTO if the traffic cannot be routed to the WTRU's currentlocation. However, if the SIPTO or LIPA traffic may be routed across theRAN, the WTRU may not deactivate ISR when SIPTO or LIPA is initiated.The WTRU may decide on activation or deactivation based on aconfiguration or on indications from the network.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A method of off-loading traffic, by an evolvedNode-B (eNB), the method comprising: transmitting, to a wirelesstransmit/receive unit (WTRU), a broadcast system information (SI)message of a Long Term Evolution (LTE) system indicating that trafficoff-load (TO) is supported; after transmitting the broadcast SI message,transmitting a non-access stratum (NAS) message to the WTRU, wherein theNAS message indicates that a TO service is available for the WTRU;receiving, from the WTRU, a signaling for initiating TO service inresponse to at least transmitting the NAS message; and communicatingusing the TO service while maintaining at least one bearer with theWTRU.
 2. The method of claim 1, wherein the eNB corresponds to a Homeevolved Node B (HeNB).
 3. The method of claim 1, wherein the NAS messageis an Attach Accept message.
 4. The method of claim 1, wherein the NASmessage is a Tracking area update Accept message.
 5. The method of claim1, wherein the TO service is received through non-3GPP access.
 6. Themethod of claim 5, wherein the non-3GPP access includes any of: aWireless Local Area Network (WLAN) and a Worldwide Interoperability forMicrowave Access (WiMAX).
 7. The method of claim 1, wherein transmittingthe NAS message to the WTRU includes transmitting the NAS message whilethe WTRU is camping on the eNB.
 8. An evolved Node-B (eNB) comprising: atransmitter configured to transmit, to a wireless transmit/receive unit(WTRU), a broadcast system information (SI) message of a Long TermEvolution (LTE) system indicating that traffic off-load (TO) issupported; the transmitter further configured to, after transmitting thebroadcast SI message, transmit a non-access stratum (NAS) message to theWTRU, wherein the NAS message indicates that a TO service is availablefor the WTRU; a receiver configured to receive, from the WTRU, asignaling for initiating TO service in response to at least thetransmitted NAS message; and a processor, operatively coupled to thetransmitter and the receiver, configured to communicate using the TOservice while maintaining at least one bearer with the WTRU.
 9. The eNBof claim 8, wherein the eNB corresponds to a Home evolved Node B (HeNB).10. The eNB of claim 8, wherein the NAS message is an Attach Acceptmessage.
 11. The eNB of claim 8, wherein the NAS message is a Trackingarea update Accept message.
 12. The eNB of claim 8, wherein the TOservice is received through non-3GPP access.
 13. The eNB of claim 12,wherein the non-3GPP access includes any of: a Wireless Local AreaNetwork (WLAN) and a Worldwide Interoperability for Microwave Access(WiMAX).
 14. The eNB of claim 8, wherein the transmitter is configuredto transmit the NAS message while the WTRU is camping on the eNB.